How children understand the concepts of teaching and learning is inherently underpinned by their mental state understanding and critical to the successful transition to formal schooling. Knowledge is a private representational mental state; learning is a knowledge change process that can be either intentional or not; and teaching is an intentional attempt to change others' knowledge state. Theory of mind (ToM) facilitates children's understanding of knowledge state and change as well as teaching and learning intention in various aspects, including knowing you do not know; knowing what other people know; knowing that other people do not know what you know; and knowing how knowledge comes about. This paper highlights the integral relation between children's ToM development and their teaching and learning concept based on review of empirical research and discusses the implication for early childhood education and school transition.